PRIMARY SEQUENCE, TISSUE-SPECIFICITY AND EXPRESSION OF THE NA-ATPASE ALPHA-1 SUBUNIT IN THE EUROPEAN EEL (ANGUILLA-ANGUILLA)(,K+)

The entire cDNA nucleotide sequence of the Na+,K+-ATPase alpha 1 isofo rm was cloned from the gills of the European eel (Anguilla anguilla) b y a PCR based method, The amino acid sequence translated from the sequ ence shared 89.4 and 85.6% homology respectively with previously publi shed Na+,K+-ATPase alpha subunit sequences from elasmobranch (Torpedo californica) and teleost (Catostomus commersoni) fish, The size of Na,K+-ATPase alpha 1 mRNA transcripts in eel tissues was demonstrated to be 3.5 kb, except in the ovary where a 3.7 kb transcript existed, Na,K+-ATPase alpha 1 mRNA was present at some level in all tissues inves tigated with the exception of cardiac and skeletal muscle where no Na,K+-ATPase alpha 1 mRNA was detectable, The level of branchial Na+,K+- ATPase alpha 1 mRNA increased after the adaptation of freshwater eels to normal or double concentration seawater.